1. Field of the Invention
The present invention relates generally to armor systems and in particular to a method for determining the presence of cracks and other broken components in a piece of armor.
2. Background of the Invention
Many high performance armor systems contain ceramic components that are subject to cracking and fracture during normal operations in the field. Cracks form readily due to the brittle nature of ceramic materials, including a low fracture toughness. Furthermore, a cracked component will not exhibit the same tensile or compressive strength as a pristine, undamaged component. Thus, a cracked ceramic component may serve to compromise the ballistic integrity of an armor system in which it is embedded, particularly for impacts near the crack or damaged region. The problem is compounded by the fact that when a ceramic component is embedded in a system, such as an armor system, it may be virtually inaccessible to visual inspection to detect cracks or other damage.
Traditional methods for determination of crack formation in a ceramic body, over and above visual inspection, include X-ray or ultrasonic detection methods, as taught in, for example, “Acoustic Techniques for the Inspection of ballistic Protective Inserts in Personnel Armor,” SAMPE Journal, September/October, 2003, pp. 1–8. Both of the latter techniques, while useful in a laboratory setting, are much less practical in a “field” setting, such as a combat area, due to their lack of portability. Other techniques for detection of cracks in ceramics include electrical measurement of a ceramic with one surface immersed in a conductive liquid, as taught in U.S. Pat. No. 5,969,532 to Usui. The latter technique, however, may not lend itself to use in “field” settings where immersion of a ceramic in a liquid may not be feasible.
In light of the above discussion, it will be appreciated that a need exists for improvements in detecting defects in a convenient manner in ceramic and related systems.